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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: zinedine_88 on April 09, 2008, 01:27:20 PM

Title: HW PROBLEM - please *delete me*
Post by: zinedine_88 on April 09, 2008, 01:27:20 PM

the problem is


What mass of METHANE is needed to heat up 285 grams of water from 42 degrees Celsius to 106 degrees celsius...



I tried whatever I could... but the computer doesn't get the answer..

thanks...

Title: Re: HW PROBLEM - please *delete me*
Post by: sjb on April 09, 2008, 02:33:42 PM

Let's see your working, and see if it's a problem there, or with the computer program....

Title: Re: HW PROBLEM - please *delete me*
Post by: MrOHBrown on April 09, 2008, 05:59:38 PM

You will need to first determine the total energy output (Heat of combustion) required for that much of a temperature change in water

Heat required = - (mass of water) x (specific heat of water) x (change in temperature)

Use the molar heat of combustion of methane to determine how many moles of methane is required and use your mole conversion equation to change that to a mass value.

There should be a tonne of websites explaining this.

Title: Re: HW PROBLEM - please *delete me*
Post by: zinedine_88 on April 09, 2008, 08:04:13 PM

i got it

there was a miscalculation cuz i had to assume that the water that is a product of the combustion of METHANE is a STEAM.... , not a liquid...thanks everybody

no u can delete it...